This invention relates to sealing of a housing, such as optoelectronic packaging, in a manner to restrain material given off by sealants used in the housing from contaminating the interior of the package, and more particularly, to sealing of an optical passage, such as a window or optical fiber, within a hermetic package in a manner to limit materials given off by sealants such as organic adhesives from access to the interior of the hermetic package.
Many optical applications that require the use of adhesives (bonding materials) to adhere (bond) elements to some type of holder may require hermetic sealing of the device. Using adhesives such as epoxy can present problems with hermetic seals because the adhesives can outgas such things as water and components, such as solvents. As a result, it is highly desirable to seal the exposed adhesive surface to prevent outgasing of any adhesive components.
For example, optical fibers may be threaded through a precision opening (aperture) in a support member (substrate) that is, or is intended to be, part of a hermetically sealed package. It is convenient in such a situation to seal the fiber to the sides of the opening using an adhesive, such as epoxy. Unfortunately, this results in exposed adhesive within the intended hermetic package. Since many adhesives, such as epoxy, outgas, or give off undesirable materials such as water or solvents, this may result in contamination of the interior of the hermetic package with the resulting outgased materials.
The prior art has been aware of the problem of outgasing from organic adhesives into hermetic enclosures, but the usual solution is to either avoid adhesives prone to outgasing entirely, or at least attempt to reduce the outgasing, or to remove the products of outgasing after sealing the hermetic container.
From a first apparatus aspect, the present invention is a packaging member for forming at least part of a hermetic package having a portion thereof for forming an interior surface of a hermetic package and having at least one side wall which at least partly defines an opening therethrough. The packaging member comprises an optical element passing through the opening in the packaging member, bonding material, and a layer of sealing material. The bonding material bonds the optical element to at least a portion of the one side wall of the packaging member and has a surface adjacent the portion of the housing member for forming an interior surface. The bonding material is prone to emission of undesirable components into the interior of the hermetic package. The layer of sealing material covers the surface of the bonding material adjacent the portion of the housing member. The layer of sealing material is one which is not prone to emission of undesirable components and which limits undesirable components emitted from the bonding material from entering the interior of the hermetic package.
From a second apparatus aspect, the invention is an array apparatus which comprises a substrate, N elements, a bonding material, and a layer of sealing material. The substrate is capable of supporting an array of N spaced-apart elements and has first and second opposing surfaces and defines a plurality of N substrate apertures which each extend therethrough from the first surface to the second surface with a cross-section of each of the N substrate apertures being greater than a cross-section of an element such that one element can be passed through in each of the N primary substrate apertures. Each one of the N elements has an end that passes through one of the N spaced-apart apertures in the substrate with the end extending sufficiently through an aperture in the substrate to have a surface that is at least essentially common with the second surface of the substrate. The bonding material is located in each aperture in the substrate and bonds each element to the substrate. The bonding material has a surface adjacent the second surface of the substrate and is prone to emission of undesirable components through the adjacent surface. The layer of sealing material covers the adjacent surface of the bonding material. The sealing material is one which is not prone to emitting undesirable components and which limits the emission of undesirable components from the bonding material from passing therethrough.
From a third apparatus aspect, the present invention is an optical fiber array apparatus which comprises a substrate, N optical fibers, a bonding material, and a layer of sealing material. The substrate is capable of supporting an array of N spaced-apart optical fibers and has first and second opposing surfaces and defines a plurality of N substrate apertures which each extend therethrough from the first surface to the second surface with a cross-section of each of the N substrate apertures being greater than a cross-section of an optical fiber such that one optical fiber can be passed through in each of the N substrate apertures. Each one of the N optical fibers has an end that passes through one of the N spaced-apart apertures in the substrate with the end extending sufficiently through an aperture in the substrate to have a surface that is at least essentially common with the second surface of the substrate; The bonding material is located in each aperture in the substrate and bonding each optical fiber to the substrate. The bonding material has a surface adjacent the second surface of the substrate and is prone to emission of undesirable components through the adjacent surface. The layer of sealing material covers the adjacent surface of the bonding material. The sealing material is one that is not prone to emitting undesirable components and which limits the emitted undesirable components from the bonding material from passing therethrough.
From a fourth apparatus aspect, the invention is a hermetic package which comprises a packaging member, an optical element, a bonding material, a layer of sealing material, and an additional member. The packaging member forms at least part of a hermetic package and has a portion thereof for forming an interior surface of a hermetic package. The packaging member defines an opening extending there through. The optical element passes through the opening in the packaging member. The bonding material bonds the optical element to the packaging member. The bonding material has a surface adjacent the portion of the housing member for forming an interior surface. The bonding material is prone to emission of undesirable components into the interior of the hermetic package. The layer of sealing material is on and covers the surface of the bonding material adjacent the portion of the housing member. The layer of sealing material is not prone to emitting undesirable components and limits undesirable components emitted by the bonding material from entering the interior of the hermetic package. The additional member is attached to the packaging member to form a complete hermetically sealed package.
From a fifth apparatus aspect, the invention is a packaging member which has a portion thereof for forming an interior surface of a hermetic package and which defines an opening therethrough. The packaging member comprises an optical fiber passing through the opening in the packaging member, epoxy resin bonding material, and a layer of sealing material. The epoxy resin bonding material bonds the optical element to the packaging member. The epoxy resin bonding material has a surface adjacent the portion of the housing member for forming an interior surface. The bonding material is prone to emission of undesirable components into the interior of the hermetic package. The layer of a sealing material is on and covers the surface of the bonding material adjacent the portion of the housing member. The sealing material is one which limits emission of undesirable components into an interior of a hermetic package of which the packaging member forms a part. The layer of sealing material limits undesirable components emitted by the bonding material from entering the interior of the hermetic package and is selected from the group consisting of chromium, copper, gold, tungsten, titanium, nickel, and aluminum, and has a thickness of about 0.03 microns or greater.
From a sixth apparatus aspect, the invention is a packaging member, which forms at least part of a hermetic package, has side walls which define an opening therethrough, and has a portion thereof for forming an interior surface of the hermetic package. The packaging member comprises a connector element passing through the opening in the packaging member, a bonding material, and a layer of sealing material. The bonding material bonds the connector element to the side walls which define the opening. The bonding material has a surface adjacent the portion of the housing member for forming an interior surface. The bonding material is prone to emission of undesirable components into the interior of hermetic package. The layer of sealing material is on and covering the surface of the bonding material adjacent the portion of the housing member. The layer of sealing material is not prone to emitting undesirable components and limits undesirable components emitted by the bonding material from entering the interior of the hermetic package.
From a first method aspect, the invention is a process of sealing an optical element bonded to a support member using bonding material. The method comprises the steps of: placing an optical element through an opening in the support member with the cross-section of the opening being greater than the cross-section of the optical element and with the optical element projecting beyond the support member; filling a space between the optical element and the support member with a bonding material which is prone to emit undesirable components; coating the bonding material and the projecting portion of the optical element with a layer of material which is not prone to emitting undesirable components and which limits passage of any undesirable components emitted by the bonding material; and removing that portion of the layer of material which coats the projecting portion of the optical element while leaving that portion of the layer of material which coats the bonding material intact.
From a seventh apparatus aspect the invention is a packaging member that forms at least part of a hermetic package that defines an opening therethrough and has a portion thereof for forming an interior surface of the hermetic package. The packaging member comprises a connector element passing through the opening in the packaging member, a bonding material, and a layer of sealing material. The bonding material bonds the connector element to the packaging member. The bonding material has a surface adjacent the portion of the packaging member for forming an interior surface The bonding material is prone to emission of undesirable components into the interior of the hermetic package. The layer of a sealing material is on and covers the surface of the bonding material adjacent the portion of the housing member. The layer of sealing material is not prone to emitting undesirable components and limits undesirable components emitted by the bonding material from entering the interior of the hermetic package.
From a second method aspect, the invention is a process of sealing an optical fiber bonded to a support member with epoxy resin bonding material. The method comprises the steps of: placing an optical fiber through an opening in the support member which has a cross-section which is greater than the cross-section of the optical fiber such that there is a space between the optical fiber and the support member, and the optical fiber projects beyond a surface of the support member; filling the space between the optical fiber and the support member with an epoxy resin bonding material which is prone to emit undesirable components; removing a portion of the epoxy resin bonding material so as to leave the bonding material recessed below the surface of the support member; coating the epoxy resin bonding material and the projecting portion of the optical fiber with a layer of material which layer limits passage of any undesirable components emitted by the epoxy resin bonding material; and removing that portion of the layer of material which coats the projecting portion of the optical fiber while leaving that portion of the layer of material which coats the bonding material intact and also removing the projecting portion of the optical element to leave the optical element flush with the surface of the support member.
From a third method aspect, the invention is a process of sealing an element to a support member using bonding material. The method comprises the steps of: placing an element through an opening in the support member with the cross-section of the opening being greater than the cross-section of the element and with the element projecting beyond the support member; filling a space between the element and the support member with a bonding material which is prone to emit undesirable components; coating the bonding material and the projecting portion of the element with a layer of sealing material which is not prone to emitting undesirable components and which limits passage of any undesirable components emitted by the bonding material; and removing that portion of the layer of sealing material which coats the projecting portion of the element while leaving that portion of the layer of sealing material which coats the bonding material essentially intact.
From a fourth method aspect, the invention is process of sealing an element bonded to a support member using epoxy resin bonding material. The method comprises the steps of: placing an element through an opening in the support member which has a cross-section which is greater than the cross-section of the element such that there is a space between the element and the support member, and the element projects beyond a surface of the support member; filling the space between the element and the support member with an epoxy resin bonding material which is prone to emit undesirable components; removing a portion of the epoxy resin bonding material so as to leave the bonding material recessed below the surface of the support member; coating the epoxy resin bonding material and the projecting portion of the element with a layer of sealing material which is not prone to emitting undesirable components and which limits passage of any undesirable components emitted by the epoxy resin bonding material; and removing that portion of the layer of sealing material which coats the projecting portion of the element while leaving that portion of the layer of sealing material which coats the bonding material essentially intact and also removing the projecting portion of the element to leave the element flush with the surface of the support member.
The invention will be better understood from the following more detailed description taken in conjunction with the accompanying drawings and claims.